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TINC.CONF(5) BSD File Formats Manual TINC.CONF(5)

NAME

tinc.conf — tinc daemon configuration

DESCRIPTION

The files in the /etc/tinc/ directory contain runtime and security information for the tinc daemon.

NETWORKS

It is perfectly ok for you to run more than one tinc daemon. However, in its default form, you will soon notice that you can’t use two different configuration files without the −c option.

We have thought of another way of dealing with this: network names. This means that you call tinc.conf with the −n option, which will assign a name to this daemon.

The effect of this is that the daemon will set its configuration root to /etc/tinc/NETNAME/, where NETNAME is your argument to the −n option. You’ll notice that messages appear in syslog as coming from tincd.NETNAME.

However, it is not strictly necessary that you call tinc with the −n option. In this case, the network name would just be empty, and it will be used as such. tinc now looks for files in /etc/tinc/, instead of /etc/tinc/NETNAME/; the configuration file should be /etc/tinc/tinc.conf, and the host configuration files are now expected to be in /etc/tinc/hosts/.

But it is highly recommended that you use this feature of tinc, because it will be so much clearer whom your daemon talks to. Hence, we will assume that you use it.

NAMES

Each tinc daemon should have a name that is unique in the network which it will be part of. The name will be used by other tinc daemons for identification. The name has to be declared in the /etc/tinc/NETNAME/tinc.conf file.

To make things easy, choose something that will give unique and easy to remember names to your tinc daemon(s). You could try things like hostnames, owner surnames or location names.

PUBLIC/PRIVATE KEYS

You should use tincd -K to generate public/private keypairs. It will generate two keys. The private key should be stored in a separate file /etc/tinc/NETNAME/rsa_key.priv −− where NETNAME stands for the network (see NETWORKS) above. The public key should be stored in the host configuration file /etc/tinc/NETNAME/hosts/NAME −− where NAME stands for the name of the local tinc daemon (see NAMES).

SERVER CONFIGURATION

The server configuration of the daemon is done in the file /etc/tinc/NETNAME/tinc.conf. This file consists of comments (lines started with a #) or assignments in the form of:

Variable = Value.

The variable names are case insensitive, and any spaces, tabs, newlines and carriage returns are ignored. Note: it is not required that you put in the = sign, but doing so improves readability. If you leave it out, remember to replace it with at least one space character.

Here are all valid variables, listed in alphabetical order. The default value is given between parentheses.

AddressFamily = ipv4 | ipv6 | any (any)

This option affects the address family of listening and outgoing sockets. If "any" is selected, then depending on the operating system both IPv4 and IPv6 or just IPv6 listening sockets will be created.

BindToAddress = address [experimental]

If your computer has more than one IPv4 or IPv6 address, tinc will by default listen on all of them for incoming connections. It is possible to bind only to a single address with this variable.

This option may not work on all platforms.

BindToInterface = interface [experimental]

If your computer has more than one network interface, tinc will by default listen on all of them for incoming connections. It is possible to bind only to a single interface with this variable.

This option may not work on all platforms.

BlockingTCP = yes | no (
no) [experimental]

This options selects whether TCP connections, when established, should use blocking writes. When turned off, tinc will never block when a TCP connection becomes congested, but will have to terminate that connection instead. If turned on, tinc will not terminate connections but will block, thereby unable to process data to/from other connections. Turn this option on if you also use TCPOnly and tinc terminates connections frequently.

ConnectTo = name

Specifies which other tinc daemon to connect to on startup. Multiple ConnectTo variables may be specified, in which case outgoing connections to each specified tinc daemon are made. The names should be known to this tinc daemon (i.e., there should be a host configuration file for the name on the ConnectTo line).

If you don’t specify a host with ConnectTo, tinc won’t try to connect to other daemons at all, and will instead just listen for incoming connections.

Device = device (
/dev/tap0
, /dev/net/tun or other depending on platform)

The virtual network device to use. tinc will automatically detect what kind of device it is. Note that you can only use one device per daemon. Under Windows, use Interface instead of Device. The info pages of the tinc package contain more information about configuring the virtual network device.

Hostnames = yes | no (no)

This option selects whether IP addresses (both real and on the VPN) should be resolved. Since DNS lookups are blocking, it might affect tinc’s efficiency, even stopping the daemon for a few seconds every time it does a lookup if your DNS server is not responding.

This does not affect resolving hostnames to IP addresses from the host configuration files.

Interface = interface

Defines the name of the interface corresponding to the virtual network device. Depending on the operating system and the type of device this may or may not actually set the name of the interface. Under Windows, this variable is used to select which network interface will be used. If you specified a Device, this variable is almost always already correctly set.

KeyExpire = seconds (3600)

This option controls the period the encryption keys used to encrypt the data are valid. It is common practice to change keys at regular intervals to make it even harder for crackers, even though it is thought to be nearly impossible to crack a single key.

MACExpire = seconds (600)

This option controls the amount of time MAC addresses are kept before they are removed. This only has effect when Mode is set to "switch".

MaxTimeout = seconds (900)

This is the maximum delay before trying to reconnect to other tinc daemons.

Mode = router | switch | hub (router)

This option selects the way packets are routed to other daemons.

router

In this mode Subnet variables in the host configuration files will be used to form a routing table. Only unicast packets of routable protocols (IPv4 and IPv6) are supported in this mode.

This is the default mode, and unless you really know you need another mode, don’t change it.

switch

In this mode the MAC addresses of the packets on the VPN will be used to dynamically create a routing table just like an Ethernet switch does. Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode at the cost of frequent broadcast ARP requests and routing table updates.

This mode is primarily useful if you want to bridge Ethernet segments.

hub

This mode is almost the same as the switch mode, but instead every packet will be broadcast to the other daemons while no routing table is managed.

Name = name [required]

This is the name which identifies this tinc daemon. It must be unique for the virtual private network this daemon will connect to.

PingTimeout = seconds (60)

The number of seconds of inactivity that tinc will wait before sending a probe to the other end. If that other end doesn’t answer within that same amount of time, the connection is terminated, and the others will be notified of this.

PriorityInheritance = yes | no (
no) [experimental]

When this option is enabled the value of the TOS field of tunneled IPv4 packets will be inherited by the UDP packets that are sent out.

PrivateKey = key [obsolete]

The private RSA key of this tinc daemon. It will allow this tinc daemon to authenticate itself to other daemons.

PrivateKeyFile = filename (
/etc/tinc/NETNAME/rsa_key.priv
)

The file in which the private RSA key of this tinc daemon resides. Note that there must be exactly one of PrivateKey or PrivateKeyFile specified in the configuration file.

TunnelServer = yes | no (
no) [experimental]

When this option is enabled tinc will no longer forward information between other tinc daemons, and will only allow nodes and subnets on the VPN which are present in the /etc/tinc/NETNAME/hosts/ directory.

HOST CONFIGURATION FILES

The host configuration files contain all information needed to establish a connection to those hosts. A host configuration file is also required for the local tinc daemon, it will use it to read in it’s listen port, public key and subnets.

The idea is that these files are portable. You can safely mail your own host configuration file to someone else. That other person can then copy it to his own hosts directory, and now his tinc daemon will be able to connect to your tinc daemon. Since host configuration files only contain public keys, no secrets are revealed by sending out this information.

Address = address [recommended]

The IP address or hostname of this tinc daemon on the real network. This wil only be used when trying to make an outgoing connection to this tinc daemon. Multiple Address variables can be specified, in which case each address will be tried until a working connection has been established.

Cipher = cipher (blowfish)

The symmetric cipher algorithm used to encrypt UDP packets. Any cipher supported by OpenSSL is recognised. Furthermore, specifying "none" will turn off packet encryption. It is best to use only those ciphers which support CBC mode.

Compression = level (0)

This option sets the level of compression used for UDP packets. Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib), 10 (fast lzo) and 11 (best lzo).

Digest = digest (sha1)

The digest algorithm used to authenticate UDP packets. Any digest supported by OpenSSL is recognised. Furthermore, specifying "none" will turn off packet authentication.

IndirectData = yes | no (no)

This option specifies whether other tinc daemons besides the one you specified with ConnectTo can make a direct connection to you. This is especially useful if you are behind a firewall and it is impossible to make a connection from the outside to your tinc daemon. Otherwise, it is best to leave this option out or set it to no.

MACLength = length (4)

The length of the message authentication code used to authenticate UDP packets. Can be anything from "0" up to the length of the digest produced by the digest algorithm.

PMTU = mtu (
1514) [experimental]

This option controls the initial path MTU to this node.

PMTUDiscovery = yes | no (
no) [experimental]

When this option is enabled, tinc will try to discover the path MTU to this node. After the path MTU has been discovered, it will be enforced on the VPN.

Port = port (655)

The port number on which this tinc daemon is listening for incoming connections.

PublicKey = key [obsolete]

The public RSA key of this tinc daemon. It will be used to cryptographically verify it’s identity and to set up a secure connection.

PublicKeyFile = filename [obsolete]

The file in which the public RSA key of this tinc daemon resides.

From version 1.0pre4 on tinc will store the public key directly into the host configuration file in PEM format, the above two options then are not necessary. Either the PEM format is used, or exactly one of the above two options must be specified in each host configuration file, if you want to be able to establish a connection with that host.

Subnet = address[/prefixlength]

The subnet which this tinc daemon will serve. tinc tries to look up which other daemon it should send a packet to by searching the appropriate subnet. If the packet matches a subnet, it will be sent to the daemon who has this subnet in his host configuration file. Multiple Subnet variables can be specified.

Subnets can either be single MAC, IPv4 or IPv6 addresses, in which case a subnet consisting of only that single address is assumed, or they can be a IPv4 or IPv6 network address with a prefixlength. Shorthand notations are not supported. For example, IPv4 subnets must be in a form like 192.168.1.0/24, where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask. Note that subnets like 192.168.1.1/24 are invalid! Read a networking HOWTO/FAQ/guide if you don’t understand this. IPv6 subnets are notated like fec0:0:0:1:0:0:0:0/64. MAC addresses are notated like 0:1a:2b:3c:4d:5e.

TCPOnly = yes | no (no)

If this variable is set to yes, then the packets are tunnelled over the TCP connection instead of a UDP connection. This is especially useful for those who want to run a tinc daemon from behind a masquerading firewall, or if UDP packet routing is disabled somehow. Setting this options also implicitly sets IndirectData.

SCRIPTS

Apart from reading the server and host configuration files, tinc can also run scripts at certain moments. Under Windows (not Cygwin), the scripts should have the extension .bat.

/etc/tinc/NETNAME/tinc-up

This is the most important script. If it is present it will be executed right after the tinc daemon has been started and has connected to the virtual network device. It should be used to set up the corresponding network interface, but can also be used to start other things. Under Windows you can use the Network Connections control panel instead of creating this script.

/etc/tinc/NETNAME/tinc-down

This script is started right before the tinc daemon quits.

/etc/tinc/NETNAME/hosts/HOST-up

This script is started when the tinc daemon with name HOST becomes reachable.

/etc/tinc/NETNAME/hosts/HOST-down

This script is started when the tinc daemon with name HOST becomes unreachable.

The scripts are started without command line arguments, but can make use of certain environment variables. Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts. Under Windows, in .bat files, they have to be put between % signs.

NETNAME

If a netname was specified, this environment variable contains it.

NAME

Contains the name of this tinc daemon.

DEVICE

Contains the name of the virtual network device that tinc uses.

INTERFACE

Contains the name of the virtual network interface that tinc uses. This should be used for commands like ifconfig.

NODE

When a host becomes (un)reachable, this is set to its name.

REMOTEADDRESS

When a host becomes (un)reachable, this is set to its real address.

REMOTEPORT

When a host becomes (un)reachable, this is set to the port number it uses for communication with other tinc daemons.

FILES

The most important files are:

/etc/tinc/

The top directory for configuration files.

/etc/tinc/NETNAME/tinc.conf

The default name of the server configuration file for net NETNAME.

/etc/tinc/NETNAME/hosts/

Host configuration files are kept in this directory.

/etc/tinc/NETNAME/tinc-up

If an executable file with this name exists, it will be executed right after the tinc daemon has connected to the virtual network device. It can be used to set up the corresponding network interface.

/etc/tinc/NETNAME/tinc-down

If an executable file with this name exists, it will be executed right before the tinc daemon is going to close its connection to the virtual network device.

SEE ALSO

tincd(8), http://www.tinc-vpn.org/, http://www.linuxdoc.org/LDP/nag2/.

The full documentation for tinc is maintained as a Texinfo manual. If the info and tinc programs are properly installed at your site, the command info tinc should give you access to the complete manual.

tinc comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions; see the file COPYING for details.

February 26, 2011

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